How do you determine the right size generator?

[Felonious Monk/Fignozzle]

I'm considering the purchase of an emergency generator, and I see a variety of sizes and prices.  Here in AL, we get hit with hurricane and tornado weather, but that's about it.

Do you buy one with the intention of running the entire house, just a hot pot and a lamp, or

Do you buy it and plan for a month-long blackout, or a couple of hours, or

I'm just not sure what to factor in to such a purchase.
Any suggestions?

[Art Eatman]

I have two, which I got as "good used".  A light-duty 2500 that's portable.  Good to run the refrigerator and small stuff around the house or out and about around the ranch.  A 5KW which would run a whole house, including conventional A/C.  I don't really need that much, given my propane cookstove and water heater.

The capacitor-start load of a refrigerator is some 20 amps; running, it draws around 8.  So, you need 20 x 120, roughly, for a minimum size if you want to run your refrigerator in the usual fashion.  A 2500-watt, then.  Now, it won't hurt things to have your TV and/or computer on; a momentary flicker at startup is all.

The longest outage we've had here is some 40 hours.  Normally, no more than two to four hours.  If night time, I don't really worry; just go to bed early.  Daytime in summer, I mostly just run the evaporative cooler and a light or two plus either the TV or the computer.  (Yeah, I know; evap coolers don't work in Alabama. )

For a good standby unit, I'd figure on intermittent use.  Daytime, give it a rest every tankful of gasoline or thereabouts.  If you don't open the refrigerator regularly, it only needs to run about an hour or so every six to eight hours.  In hot summer, kill out the breakers for unnecessary stuff so you can have the A/C.

Overall?  Add up the amps for "gotta have" loads.  I use 60-watt light bulbs; I call them one amp just for conseratism's sake.  Amps times 120 or 240 = watts.  If you don't run full load on your generator, it'll do fine for constant use.

I'm not impressed by the mufflers they come with, though.  A 5KW will quite possibly annoy the neighbors.

Don't leave any fuel in the tank during non-use.  Test it with a minimal amount of gas in the tank and then run it dry.  If you can easily disconnect the fuel line to the carburetor, give it a brief shot of WD 40 and crank the engine a bit before storage.  If you really want it ready and fueled, use StaBil.

If the carb cruds up from sittiing, spray carb cleaner through the fuel line is a Good Thing.  Check and write down stuff like the number of turns of the idle mixture screw from "runs good" to "closed".  That way you can pull it and spray carb cleaner in the hole.  Same for any other sort of adjustment screw.  No magic to it.

Read the directions.  Make sure they're in a "keeper" place.

Art

[Lee]

I'm going through the same exercise myself.  The Coleman site is pretty useful.  

http://www.colemanpowermate.com/powerstation/wattage_wizard.shtml

[LAK]

Add up the sum total of your requirements - and double it. It will then provide all your needs - and some that might arise impromptu - without any strain. We have a 5,500 watt unit we picked as a reconditioned factory return at $400 a few years back.

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http://ussliberty.org
http://ssunitedstates.org

[280plus]

FWIW-

Here in CT there's a new .gov program where if you put a generator at your business and agree to go off the grid and on to it during crisis type peak demand you get a pretty good rebate.

[grampster]

Mine is a 5500 watt.   Get a duplicate service box that corresponds to what you have now.  (ie:  100 amp, 150 amp service)  Route your entire service to the second box through a transfer switch that you'll need to stop backfeeding the commercial line when the power comes on.  When the power goes out, you throw the transfer switch, cranak up the generator and then shut off the circuits you don't need at the box.  The reason you transfer the whole house to the 2nd service is that you can shut off or turn on which circuits you need at any given moment.  I have a plug on the outside of the house that I hook my generator to route the power to the 2nd box.

Get a generator with a Honda motor.  You don't need to buy the Honda generator as it's very expensive.  The Honda motor is quieter and more reliable imho.  their are a number of generators that are Honda powered.

Mine runs a furnace, a well pump, a lift pump to my septic drain field, two refrigerators, a micro wave and lights in any given room.  5500 will not run A/C and I don't have my electric range hooked up either.  Microwave or gas grille will cook anything we need.

[Guest]

Note that the 'starting load'  or surge load for electric motors is a good bit higher than the 'running load.'  You need to size your generator to start the largest appliance you want to run with it, which might mean firguring twice as much capacity to start as to run.  See one of the many generator load calculators available on the web ( http://www.usdieselengines.com/power_calculator.htm for example), work up a list of what you want to run, and go from there.

Be careful, educate yourself thoroughly about using generators and hooking them up so you don't backfeed power into the grid- you could kill someone who's trying to restore power.

lpl/nc

[Felonious Monk/Fignozzle]

Lee-- VERY nice to see you!  Don't be such a stranger.

Grampster, all-- I've also seen some ads for generators with this "Robin/Subaru" motor that claims to be better than the Honda...

Not sure what to think of that...any opinions?

The Honda quality's unquestionable, and they know it in the sales price.  Coleman, some others use the Honda motors, that might be the better way to go.